It is well known that some micro-organisms such as Aspergillus oryzae, Aspergillus parasiticus, Mycobacterium phlei, Aeromonas proteolytica, Bacillus subtilis, and Bacillus stearothermophilus can produce enzymes which are capable of hydrolyzing .alpha.-amino acid amides so as to form .alpha.-amino acid in an aqueous medium.
These prior art enzymes which in the following are referred to as .alpha.-amino acyl amidases show a highly stereo-specific activity and hydrolyze only L-.alpha.-amino acyl amides. Thus, D-.alpha.-amino acyl amides are substantially unaffected by these enzymes.
Therefore, these .alpha.-amino acyl amidases are suitable for effecting an optical resolution of DL-.alpha.-amino acids. In such a process, .alpha.-amino acyl amidase is contacted with DL-.alpha.-amino acid amide to effect a hydrolysis of the L-.alpha.-amino acid amide to form the corresponding amino acid, and the amino acid formed and/or the remaining D-.alpha.-amino acid amide is isolated [Greenstein & Winitz: "Chemistry of the amino-acids", vol. 3, pp. 1778-1781 (New York 1961)].
The object of the invention is to provide a preparation having an improved L-.alpha.-amino acyl amidase activity compared to the preparations obtained by the above-mentioned prior art method.
A further object of the invention is to provide a preparation having a high L-.alpha.-amino acyl amidase activity and without undesired enzymatic side effects.
A still further object of the invention is to provide a process of preparing L-.alpha.-amino acid and/or D-.alpha.-amino acid amide from DL-.alpha.-amino acid amide.